The present invention refers to a hydraulic shock absorber with progressive braking effect.
More particularly, the present invention relates to a hydraulic shock absorber with progressive braking effect comprising a cylinder fixed to the body filled with a fluid and a piston sliding in the cylinder and dividing it into two sequential chambers.
The piston slides in the cylinder causing the fluid to move from the lower chamber to the upper chamber, and vice versa, through ports and compression and extension valves with and progressive opening/closing, with passages with calibrated and/or variable geometry.
The hydraulic shock absorber of the present invention is particularly suitable for transportation and competition vehicles.
It s known that, in the suspension systems of the conventional transportation and competition vehicles, the oscillations derived from the reactions occurring on the suspension elastic components, in relation to the conditions of contact and adherence with the ground, are controlled be means of hydraulic shock absorbers with braking effect.
It is also known that, according to a generic evaluation and taking into account the fact that the magnitude of the braking effect affects the behaviour of the vehicles while they are running, the adoption of shock absorbers with relatively more braked action makes it possible to obtain better vehicle stability, but affects negatively their comfort. On the other hand the adoption of shock absorbers with less braked action produces opposite conditions, i.e. it makes it possible to obtain better comfort to the detriment of stability. In practice, the braking effect of the shock absorbers, in their extension and compression movements, is regulated according to compromise standards, depending on the specific intended uses of the vehicles and/or the particular tastes and requirements of the users.
A significant aspect to be evaluated when regulating the braking effect of shock absorbers is the load which can or must be borne by the vehicles. Depending on the load applied, the elastic suspension components react and are compressed, by reducing in length, for corresponding valves.
An erroneous evaluation of the braking effect, which may be more or less powerful depending on the load, may jeopardise the correct stability of the vehicles in motion.
Oscillation and/or instability phenomena related to the load can also be detected in vehicles in special situation of operation, such as, for example, sustained run on courses with turns, sudden accelerations and/or application of the brakes. For example, it is known that, in the case of curvilinear motion, a sudden change occurs in the distribution of weights, due to the effect of the centrifugal force. A considerable part of the load borne by the inside wheels, in turn, is transferred to the outside wheels and this effect produces greater compression of the elastic components of the corresponding suspensions, with proportional increase of the magnitude of their reactions and consequent requirements to correct said situation by increasing the braking effect of the shock absorbers, in order to prevent the wheel from bouncing. On the other hand, the inverse phenomenon occurs on the suspensions of the inside wheel, on which the load is lightened. Since the magnitude of the reaction of the elastic components, due to the lower load, is reduced, the shock absorbers undergo distension which requires a proportionally reduced braking effect, so that the wheel may correctly follow the condition of the course. Similar phenomena occur in the case of sudden acceleration and/or application of the brakes, in which the more loaded axle benefits from a greater braking effect of the shock absorbers and the less loaded axle benefits from the opposite, reduced braking effect. Basically, an elastic component, such as, for example, a spiral spring which, as it is compressed, reduces its length and, progressively increases the magnitude of its reaction, should operate in parallel with a shock absorber which would progressively increase its braking effect during compression. Vice-versa, as the two components distend, the braking effect should similarly be progressively reduced.
The progressive increase or decrease of the braking effect of the shock absorber can be obtained by applying, between the movable arms of the suspension and the body of the vehicles, some components, as second connectors of the shock absorbers. These components, as the geometry of the turning fulcra varies, increase or decrease the speed of the movement of the shock absorbers themselves.
However, taking into account that, in general, the elastic components use the same connectors, also the magnitude of their reactions is substantially proportionally heightened. Nevertheless, in any case, there is still a discrepancy between the magnitude of the reactions of the elastic components and the magnitude of the braking effect of the shock absorbers. This system presents also the drawback of being rather expensive and of not being very reliable because of the numerous components of the suspensions.
The object of this invention is to eliminate the above drawbacks.
In its general aspect, the present invention allows to achieve this and other objects by providing the variable volume sequential chambers of the cylinder, wherein the piston slides, with compression and extension valves with regulated and progressive opening/closing, combined with ports having variable geometry passages. Subject matter of the present invention is, therefore, a hydraulic shock absorber with progressive braking effect comprising:
a cylinder anchored to the body of the vehicle and filled with a driving fluid;
a piston anchored to a mobile component of a suspension and sliding axially into said cylinder; said piston dividing the sliding seat into two sequential coaxial chambers; and
means for connecting said chambers between them and through which the driving fluid is thrusted into one or the other chamber depending on the compression and/or extension action of the piston,
wherein, the connection means consist of (i) at least one stationary component, having optionally a variable section, which is engaged by introduction into a stationary opening of the piston and (ii) calibrates section passages with an adjustable and progressive closing/opening, depending on the pressure of the driving fluid.
The advantages achieved by the hydraulic shock absorber with progressive braking effect of the present invention consist essentially in that, to each change of distension and/or compression travel of the suspensions, deriving from variations of load or of speed, corresponds a proportional travel of the pistons of the shock absorbers, whose braking effect is automatically regulated by the proportional opening/closing of the passage ports. Said adjustments are obtained by means of opening/closing variable geometry ports with through sections proportional to the compression and/or extension travel of the shock absorbers, as well as by means of progressive opening/closing of compression and extension valves associated with the sequential chambers of the shock absorbers. The progressively opening ports and the valves may also be provided with external means of adjustment, on which it is possible to intervene simply and rapidly, so as to modify the intervening behaviour of the braking effect of the shock absorbers, as a function of the load, speed and/or the users"" particular tastes or guide requirements.
Another advantage consists in that the hydraulic shock absorbers with progressive braking effect are applicable to recreational or competition automobiles and motorcycles, with possible equal conditions of possible intervention on external means of adjusting the opening/closing of the variable geometry ports and of the compression and extension valves.
The present invention and its aspect will be more readily understood from the following description of the accompanying drawings showing some embodiments of the hydraulic shock absorber of the present invention and in which: